<!DOCTYPE html>
<html>
<head>
    <title>页面标题</title>
    <meta charset="utf-8">
    <script type="text/javascript">
        window.onload = function(){
            document.getElementById("btn1").onclick = function(){
                window.open("a.html","_blank")
            };
        }
    </script>
</head>

<body>
<!--所有布局都放在admin-main内部-->
<div>
    <input type="button" value="打开窗口" id="btn1">
</div>

</body>

</html>